Roof



June 1o, 1947. C O F 2,422,010

ROOF

Filed Nov. 22, 1944 fiavemiar %&A%

- rneys Patented June 10, 1947 'U lATE NT OFFICE noor David 0. Gofl, Omaha, Ncbr. Application November 22, 1944, Serial No. 564,679

6 Claims.

1 'The present invention relates to structural and functional improvements in roof coverings for relatively fiat supporting roof structures or decks.

Such roofs are broadly referred to in the art as fiat roofs, and in prior art practice are generally topped with layers of roofing felt bonded together by suitable adhesives. The customary procedure inapplylng a roof and insulation over a deck or relatively fiat supporting structure of concrete, steel, tile, wood, or the like, is to cement sheets or blocks of organic, moisture-absorbent heat-insulating material directly over the supporting structure or deck and then apply successive layers of felt plies and a suitable hardening adhesive, such as asphalt, coal tar pitch or other bitumen, over the organic, moisture-absorbent heat-insulating material to form the moisture-repellent surface of the roof. These so- (Cl. 102x 1 called built-up roofs, although quite universalthis" character must be inspected. repaired, and recoated with adhesive every few years, and that the average life of such roofs is approximately ten to fifteen years, after which they must be extensively repaired or completely renewed. Not only is it necessary to periodically, inspect, recoat. repair, or renew such roofs; but, wherever organic insulation is used thereunder, such insu-, lation is renewed completely whenever the roof covering fails and permits moisture to enter the insulation. Even when moisture-absorbent inorganic insulation is used, it is deprived of its insulating value when wet, and may remain wet for long periods under felt coverings. Hence, it is usually necessary to renew completely the insulation under the. roof whenever the roof has failed to any appreciable extent. It is common knowledge among the roofing trade andowners of large roof areas that commonly used roofing felts will dry out and become useless in usually not over ten years, unless they are inspected every year or two and recoated with new adhesive; this being due to the fact that the base of most felting is rag or paper stock, which deteriorates rapidly when deprived of its waterproofing adhesive; and, although there have been some inorganic roof feltings used, these also fall to provide proper moisture-proofing when deprived of their adhesive protection; it being understood that these adhesives give up their volatile oils when exposed to the sun and moisture.

It is also common knowledge among the roof-- 66 as its main ingredients Portland cement and a ing trade that no successful method has been found for laying successive layers of roofing felts over any supporting structure without such felts being apt to blister, wrinkle, buckle, or bulge afterlaying. In some cases, this is due to the fragile nature of the felts and. to stresses and strains caused'by contraction and expansion under temperature changes. In other cases, premature failure of a built-up roof due to bulges, wrinkles. and the like is due to improper application. In this conneotion, it should be,understood that it is impossible to supervise labor to be sure that each layer of felt is embedded completely and properly or that even the required amount of bonding adhesive is used. The owner of a building does not ordinarily see his roof applied due to relative inaccessibility of the roof, but the owner usually does know that his flat roof is a serious item in the maintenance cost of his building. It is further common knowledge that the so-called ,built-up" roofs are usually guaranteed for from five to ten yearsof service, or longer under some circumstances; whereas, underlying insulation sheets or blocks seldom, if ever, carry any guarantee whatsoever; this being, of course, due to the fact that the occasional easily repaired roof leak will cause a per manent failure of the insulation wetted as a result of the leak. Hence, the owner is often deprived of the benefits oi expensiveroof insulation for a number of years during the roof life. Due to the universal use of felts, most of which are organic and will rot and all of which separate and come apart at the seams, water is allowed to pocket between and under the felts and pass into the underlying insulation or other structure, where it is trapped and permitted to soak or run through rather than evaporate and .dry out, all of which is highly detrimental to the underlying insulation or supporting structure on which the felts rest. In fact, following conventional practice, these feltings are sometimes applied over underlying materials which would give better moisture and heat-insulating protection for a longer period of time had the felting been omitted.

With the above prior art practices in mind, it

may be said that an important feature of the pouring over a relatively flat supporting roof; a

structure a slabof light-weight concrete, having light-weight fireproof inorganic material such as expanded vermiculite, to a material depth, preferably well in excess of one and one-half inches, and usually over two inches. In accordance with the invention, this light-weight concrete slab is permitted to set and dry and is utilized. in itself or in combination with a thin initially liquid coating, both as the heat-insulating medium and as the water-repellent roofing. This slab provides a light-weight but solid, monolithic, jointless, water-repelling and heat-insulating layer which will serve its dual function for many years and which overcomes all of the objections above noted and otherwise commonly assigned to roofs of the so-called built-up type employing one or more layers of basically organic material or a combination of adhesively bound basically organic materials and underlying insulation. In this improved roof structure, moisture is allowed to run off of and evaporate from the roof without retardation by trapping or the like as in builtup roofs,

The improved monolithic light-weight fireproof heat-insulation and roofing is easily applied and is relatively inexpensive, since the main ingredients are easily obtained and may be mixed in ordinary mechanical mixing equipment, such as is used for mixing ordinary structural concrete, and may be thereafter handled in much the same manner as ordinary structural concrete.

While Portland cement and expanded vermiculite are proposed as the main ingredients of my light-weight concrete, it should be understood that other ingredients, such as a suitable waterproofing admix, may be, and in' fact, are preferably added to the mixture for the purpose of increasing the moisture-resisting qualities thereof. Although there are several commercially available water-repellent admixes, I have found that an asphaltic emulsion, as made by the wellknown process covered by Letters Patent of the United States Nos. 1,643,675 and 2,199,206, may be employed for the purpose; also, Vinsol" resin manufactured by Hercules Powder Company and disclosed in Letters Patent of the United States No. 2,114,393 may be used. In addition to the use of such commercially available waterproofing admixes as are disclosed in the patents identified, I have found that the moisture-repellent qualities of the product can further be materially increased by adding thereto a relatively small quantity of finely pulverized bitumen, such as commercial coal tar pitch; which may, in fact, be used either in combination with or as a substitute for other waterproofing admixes.

In accordance with the invention, ,1 expose the above described light-weight heat-insulating monolithic roof slab directly to the elements, whereby to utilize the same both as a roof heatinsulating medium and as a moisture-resisting medium. From the above it will be seen that the invention provides a monolithic heat-insulating water-repelling roof covering wherein bulging, ply separation, and other objectionable features of prior art roofs, are obviated, and which will havegreatly-increased life expectancy as compared to prior art roofs.

The above and numerous other highly important features and advantages of the invention, relating both to the product and to the method of producing the same, will be made further apparent from the following specification, claims, and appended drawings. 7

In the accompanying drawings, like charac- 4 ters indicate like parts throughout the several views.

Referring to the drawings, the single figure is a fragmentary sectional view of a building wall and roof structure embodying one form of the invention.

Referring to the drawings, a conventional masonry building wall is indicated by I0, and a conventional relatively flat roof supporting structure in the nature of a concrete roof deck is indicated by [2. However, these standard building structural elements may, insofar as this invention is concerned, be of any suitable material or type -of construction. In the drawing, the monolithic heat-insulating fireproof water-repellent roof covering slab is indicated by I4, and may be assumed to be poured to a thickness of not less than one and one-half inches, and preferably to a thickness of two or more inches. Preferably, this roof covering slab It will be of one piece over the entire roof area and is integrally formed to provide cant strips Ha at the parapet walls and to include any roofing crickets, saddles, and the like. Conventional weather-proofing at the joints between the edge of the slab and vertical walls is provided by conventional base and cap flashings i6 and I1 respectively of metal or other suitable material.

In accordance with the invention the surface of the heat-insulating water-repellent slab I4 is exposed directly to sun rays and precipitation.

The method of forming and the exact nature of the roof covering will now be more fully described as follows: The slab M is' in the nature of a light-weight concrete having as its major aggregate" expanded vermiculite of the wellknown commercial variety, and having commercially available concrete, such as Portland cement, as its binder; a preferred formula being as follows:

vermiculite aggregate cubic feet 2'7 Standard Portland cement bags 3 Waterproofing adhesive, such as has been hitherto mentioned, plus such additives as powdered coal.tar pitch orthe like gallons Water sumcient to 'produce a workable mix.

In producing the 'roof the supporting roof structure or deck -2 will usually be coated with a thin layer of moisture-repellent substance, such as hot asphalt or pitch l3 for the purpose of preventing absorption into the supporting structure of moisture from the freshly laid or poured concrete slab l4. The next step in producing the roof structure of Fig. 1 comprises pouring the batch of light-weight concrete to the desired thickness and contour to form the slab It together with its integral cant strips and the like, after which the freshly poured slab i4 is permitted to set and dry.

Suitable waterproofing admixes, such as the before mentioned type of admixes disclosed in Patents 1,643,675; 2,199,206; and 2,114,393, or powdered coal tarpitch or the like, or a combination of both or their equivalents, constitute important ingredients of the slab, since they increase greatly the water-repelling qualities of the heat-insulating slab I4. While the waterproofing defined in the patents above identified and/or other waterproofing ingredients, such as coal tar pitch, have been found to be suitable for the purpose, it is appreciated that other waterp on s admixes may be employed, and which may include additives of powdered clays, hydrocarbons, and the like. The important thing, particularly in connection with the invention, is

fireproof, rot-proof, chemically inert, and suf- L ficiently water-repellent to provide complete protection against moisture; and can be expected to have exceptionally long life.

An important feature of the light-weight concrete slab I4 is the fact that it is very tough and resilient by nature and requires no expansion joints as is necessary in ordinary structural. concrete, its basic element being exfoliated or ex panded vermiculite, the chemical properties of which are alumina, silica, and magn sium. Hence, the major ingredient is inorganic, inert, and non-corrosive; and the binder employed, being Portland cement, 'is likewise inorganic and inactive, and consequently there is no'deterioration, rotting, molding, or disintegration possible in the structure, the only other ingredients of which are inorganic waterproofing substances.

It is interesting to note that the vermiculite asmgate used in this concrete will, in itself, stand temperatures up to 2400 degrees Fahrenzheit, and that the light-weight concrete, includ- ,'lng the same as an aggregate in proportions approximately as above, will withstand tempera- ;tures up to at least 1000 degrees Fahrenheit with heit of temperature difference between opposite surfaces of a slab of one inch thickness. 1

2. The structure defined in claim 1, in which said slab has an aggregate expanded vermiculite in major part, said slab further comprising a suitable bonding agent and a waterproofing additive.

3. The structure defined in claim 1, in which said slab has an aggregate expanded vermiculite in major part, said slab further comprising a suitable bonding agent and a waterproofing additive in the nature of powdered bitumen, said powdered bitumen being dispersed through the slab mass in a powdered unfused state.

4. An integrally waterproof, fireproof, heat-insulating roof covering applied over a relatively flat structural deck of a building, said roof coverlng comprising a jointless monolithic, waterproof, fireproof, concrete slab covering the entire structural deck to a depth of not less than one ,and one-half inche and having its upper sur- ,face exposed directly to the sun rays and precipitation, said slab being of substantially uniform density and composition throughout and weigh ;ing not to exceed 35 pounds per cubic foot and having a heat loss of not over 1.0 B. t. u. per hour per square foot of slab per degree Fahrenheit of temperature difference between opposite surfaces of a-slab of one inch thickness.

Portland cement as a binder; the other ingredients, namely: waterproofing agents, being in such small quantities as to be of little or no consenuence.

What I claim is:

1. An integrally waterproof, fireproof. heat-inpersed throughout 5."The structure defined inclaim 4, in which said concrete slab has as an aggregate expanded vermiculite in major part, said slab further comprising a waterproofing additive.

6. The structure defined in claim 1, in which said slab comprises expanded vermiculite in major part, Portland cement as a binding agent, and a waterproofing additive in the nature of powdered bitumen, said powdered bitumen being disthe slab mass in a powdered 4o unfused state.

DAVIDv C. GOFF.

REFERENCES CITED The following references are of record file of this patent:

UNITED STATES PATENTS in the Number 2.03am sol-menu" "Apr-38, use

Cook Aug. 1, 1931 

